/*
 * Copyright 2016 The Cartographer Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef CARTOGRAPHER_MAPPING_INTERNAL_2D_SCAN_MATCHING_TRANSLATION_DELTA_COST_FUNCTOR_2D_H_
#define CARTOGRAPHER_MAPPING_INTERNAL_2D_SCAN_MATCHING_TRANSLATION_DELTA_COST_FUNCTOR_2D_H_

#include "Eigen/Core"
#include "ceres/ceres.h"

namespace cartographer
{
    namespace mapping
    {
        namespace scan_matching
        {

            // Computes the cost of translating 'pose' to 'target_translation'.
            // Cost increases with the solution's distance from 'target_translation'.
            class TranslationDeltaCostFunctor2D
            {
            public:
                static ceres::CostFunction *CreateAutoDiffCostFunction(
                    const double scaling_factor, const Eigen::Vector2d &target_translation)
                {
                    return new ceres::AutoDiffCostFunction<TranslationDeltaCostFunctor2D,
                                                           2 /* residuals */,
                                                           3 /* pose variables */>(
                        new TranslationDeltaCostFunctor2D(scaling_factor, target_translation));
                }

                template<typename T>
                bool operator()(const T *const pose, T *residual) const
                {
                    residual[0] = scaling_factor_ * (pose[0] - x_);
                    residual[1] = scaling_factor_ * (pose[1] - y_);
                    return true;
                }

            private:
                // Constructs a new TranslationDeltaCostFunctor2D from the given 'target_translation' (x, y).
                explicit TranslationDeltaCostFunctor2D(const double scaling_factor, const Eigen::Vector2d &target_translation)
                    : scaling_factor_(scaling_factor),
                      x_(target_translation.x()),
                      y_(target_translation.y())
                {
                }

                TranslationDeltaCostFunctor2D(const TranslationDeltaCostFunctor2D &) = delete;
                TranslationDeltaCostFunctor2D &operator=(const TranslationDeltaCostFunctor2D &) = delete;

                const double scaling_factor_;
                const double x_;
                const double y_;
            };

        } // namespace scan_matching
    }     // namespace mapping
} // namespace cartographer

#endif // CARTOGRAPHER_MAPPING_INTERNAL_2D_SCAN_MATCHING_TRANSLATION_DELTA_COST_FUNCTOR_2D_H_
